The present invention relates to a piezoelectric ceramic transducer and a method of forming the same, and more particularly to a piezoelectric ceramic transducer for a compact size power circuit capable of a highly efficient power transmission.
A piezoelectric ceramic transducer for a power circuit comprises a driver section positioned in a primary side for receiving an alternating-current voltage and a power generator section having an output electrode, wherein the driver section and the power generator section are isolated by an insulation layer from each other. A first conventional piezoelectric ceramic transducer is disclosed in Japanese laid-open patent publication No. 5-206539. A second conventional piezoelectric ceramic transducer is disclosed in Japanese laid-open patent publication No. 5- 235434. A third conventional piezoelectric ceramic transducer is disclosed in Japanese laid-open patent publication No. 6-54686.
FIG. 1 is a schematic perspective view illustrative of the first conventional piezoelectric ceramic transducer which utilizes a vertical vibration in a thickness direction which is vertical to interfaces of laminated layers. The first conventional piezoelectric ceramic transducer has a first driver section 51, a second driver section 51' and a power generator section 52. The first driver section 51 and the second driver section 51' are separated by a first insulator 55. The second driver section 51' and the power generator section 52 are separated by a second insulator 55'. The first driver section 51 comprises laminations of multiple piezoelectric ceramic layers 56 which are polarized in a thickness direction and which are separated by internal electrodes 53 from each other. The second driver section 51' also comprises laminations of multiple piezoelectric ceramic layers 56' which are polarized in a thickness direction and which are separated by internal electrodes 53' from each other. The power generator section 52 comprises a single piezoelectric ceramic layer 57. Unpolarized piezoelectric ceramic layers are provided in the first and second insulators 55 and 55', so that each of the first and second insulators 55 and 55' is sintered to integrate the unpolarized piezoelectric ceramic layer. The unpolarized piezoelectric ceramic layer may be replaced by an insulating plate of other material than the unpolarized piezoelectric ceramic as a modification.
FIG. 2 is a schematic perspective view illustrative of the second conventional piezoelectric ceramic transducer which utilizes a vertical vibration in a thickness direction which is vertical to interfaces of laminated layers. The second conventional piezoelectric ceramic transducer has a driver section 61 and a power generator 62. The driver section 61 and the power generator section 62 are separated by an insulator 65. The driver section 61 comprises laminations of multiple piezoelectric ceramic layers 66 which are polarized in a thickness direction and which are separated by internal electrodes 66 from each other. The power generator section 62 comprises a single piezoelectric ceramic layer 68. An unpolarized piezoelectric ceramic layer is provided in the insulator 65, so that the insulator 65 is sintered to integrate the unpolarized piezoelectric ceramic layer. The unpolarized piezoelectric ceramic layer may be replaced by an insulating plate of other material than the unpolarized piezoelectric ceramic as a modification.
FIG. 3 is a schematic perspective view illustrative of the third conventional piezoelectric ceramic transducer. The third conventional piezoelectric ceramic transducer has a driver section 71 and a power generator section 72 which are separated by a dielectric plate 70 from each other. The driver section 71 has an electrode comprising a main electrode 74 and a feedback electrode 76 which are separated from each other. The feedback electrode 76 is connected to an input side of a power amplifier 77, whilst the main electrode 74 is connected to an output side of the power amplifier 77. The driver section 71 shows an automatic oscillation in an X-direction to convert electric signals into mechanical signals. The oscillation of the driver section 71 is transmitted through the dielectric plate 70 to the power generator section 72 so that the power generator 72 converts the transmitted mechanical signals into electric signals which are then output from output terminals 78 and 79.
The above conventional piezoelectric ceramic transducers have the insulators comprising the piezoelectric ceramic plates which are made of the same materials as the driver section or the power generator section, for which reason it is required that the insulators have a sufficient thickness for insulating the driver section and the power generator section. This makes it difficult to reduce the size of the piezoelectric ceramic transducers. This issue is common to the other piezoelectric transducers made of the other materials than ceramic.
Further, the above conventional piezoelectric ceramic transducers use the piezoelectric ceramic materials for the insulators, for which reason it is required that the insulators have a sufficient thickness for preventing dangers such as an electric shock.
Since, further, the insulators are designed to transmit the vibration, there is raised a further problem with a large noise.
In the above circumstances, it had been required to develop a novel piezoelectric ceramic transducer which is free from the above problems.